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,PAT328, Section 3, March 2001,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,CLICK TO EDIT MASTER TITLE STYLE,DYT101, Section 10, September 2002,S10-,16,SECTION 10,LAGRANGIAN BOUNDARY CONDITIONS,SINGLE POINT CONSTRAINT - SPC,Prevents a point moving in a particular direction,.,Must be initialized in the Case Control section:,SPC = SID,Any,SPCn,entries not selected in case control are ignored,.,The displacement coordinate system of the constrained gridpoint determines the direction that the constraint is applied in,.,Can be used to model boundary conditions and planes of symmetry,.,Any component in grid coordinate system can be constrained,.,Components in a grid coordinate system are referred by digits 1 to 6. Any combination is possible, e.g. 23,156,.,SPC=100,BEGIN BULK,. . .,SPC, 100, 27, 123,SPC1, 100, 156, 19, THRU, 28,ROTATIONAL BOUNDARY CONDTION SPC2,Used to model rotational boundary conditions on gridpoints,.,Must be selected in Case Control,SPC = SID,SINGLE POINT CONSTRAINT IN LOCAL COORDINATES SPC3,Used to define a single point constraint in a local coordinate system or a cascade of two local coordinate systems,.,Must be selected in Case Control,.,SPC = SID,ENFORCED MOTION,Prescribes the motion of grid points,.,Force of pressure loading -,TYPE,=,2,in,TLOAD1,definition,.,Must be selected in Case Control,.,Any loading (,TLOADn,entry) not selected in Case Control is ignored,.,Enforced motion can be prescribed in a local coordinate system.,ENFORCED GRID POINT MOTION,Specified points can have their velocity set,.,Velocity -,TYPE,=,2,in,TLOAD1,definition,TLOAD1, 100, 110, , 2, 120,DAREA,defines magnitude of translational or angular velocity per DOF,.,FORCE,defines magnitude and direction of translational velocity,.,MOMENT,defines magnitude and direction of angular velocity,.,Velocity can vary arbitrarily with time,.,The,TABLED1,entry gives the variation of velocity,.,TLOAD = 100,BEGIN BULK,.,TLOAD1, 100, 110, , 2, 120,TABLED1, 120, +,+, 0.0, 0.0, 1.0, 1.0, ENDT,FORCE, 110, 27, , -6.0, , 1.0,ENFORCED MOTION,FORCE,in,CORDXXX,If on a,FORCE,entry a,CID,is referenced, the enforced motion is processed in a local coordinate system,.,FORCE, 110, 27,2, -6.0, , 1.0,RIGID WALLS - WALL,Models a rigid plane which specified ”slave” points can not penetrate.,Used to model hard, undeformable target.,Define a point on the wall and a vector perpendicular to it, pointing towards the model.,Two kinds of contact:,PENALTY,Method: Allowed penetration. Force increases as nodes penetrate deeper.Can have friction.,KINEMATIC,MethodNodes are put back on the Surface.Impulse is applied to Nodes.Can not have friction.,WALL, 101, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 102,+,+,PENALTY,0.2,SET1, 102, 1, THRU, 1999,TIED CONNECTIONS,Two meshes with different coarseness are permanently tied together during the analysis.,Allows beam, shell and solid meshes to be tied together without the need for coinciding grid point locations.,Possible gaps between the meshes can be requested to be closed.,Not recommended in areas where stress peaks or failure is expected.,Three types of tied connections:,Two surfaces tied together,Grid points tied to a surface,Shell edge tied to a shell surface,TWO SURFACE TIED TOGETHER (RCONN),Two surfaces are permanently tied together during the analysis.,Master,surface : always attached to the,coarse,mesh.,Slave,surface : always attached to the,finer,mesh.,Lumping forces and velocities according to shape functions.,Forces:,slave points,master points,Velocities:,master points,slave points,Example:,Two solids are tied together along their common surface 7 and 8.,RCONN, 1, SURF, SURF, 7, 8,GRID POINTS TIED TO A SURFACE (RCONN),Individual grid points are tied to a surface.,Slave surface type is,GRID,and,OPTION,must be set to,NORMAL.,Master surface must be defined as a set of segments.,Only the translational degrees of freedom are tied.,Example:,The node 1 to 10 of a beam mesh are tied to the shell surface 7.,RCONN, 1, GRID, SURF, 3, 7, NORMAL,SET1, 3, 1, THRU, 10,SHELL EDGE TIED TO A SHELL SURFACE,Connects beams or shell-edges to shell elements.,Slave surface type is,GRID,and,OPTION,must be set to,SHELL.,Master surface must be defined as a set of segments.,Translational and rotational degrees of freedom are tied.,Example:,The edge grid points 1 to 10 of a shell mesh are tied to the shell surface number 7.,RCONN, 1, GRID, SURF, 3, 7, SHELL,SET1, 3, 1, THRU, 10,RIGID BODY ELEMENTS (RBE2),Defines a set of grid points that form a rigid body.,This entry allows particular degrees of freedom of a set of grid points to be tied together so that they always move the same amount.,Used to model spotwelds, but elements can not fail.,Example:,Nodes 1 to 28 will have the same displacement in x and z-direction as node 55.,RBE2,12,55,13,1,THRU,28,Instead of defining tied components, it is also possible to use the,FULLRIG,option.,This causes the set of grid points to behave like a single rigid body element.,The name of the,RBE2,will become,FR,.,Example:,Nodes 1 to 28 and 55 will behave like a rigid body. The name will be,FR12.,RBE2,12,55,FULLRIG,1,THRU,28,KINEMATIC JOIN (KJOIN),Shell to solid grid point connection.,Joins shell to solid elements by applying kinematic conditions to the shell grid points.,A normal,JOIN,would result in a hinge connection in which only the translational DOFs are coupled.,Solves the closure problem for the different DOF of shell and solid elements.,Constitutes stiff connection between shells and solids Stiffness of join is user defined.,Example:,Kjoin between solid nodes 30, 40 and 50 and shell nodes 32, 42 and 52.,All nodes within a tolerance of 1e-5 are connected.,KJOIN, 2, 333,1e-5, 0.5,SET1, 333, 30, 32, 40, 42, 50, 52,Rotation at C follows from,the motion of the system Ri,R1,R2,R3,C,SOLIDS,SHELLS,BREAKABLE JOIN (BJOIN),Defines a breakable join between shell or beam grid points.,Joins shell or beam grid points and allows for the break of the join when a failure criterion is satisfied.,Failure models :,Constant Force or Moment,Components Failure,Spotweld like behavior,User defined,Breakable join can have offset (spotweld modeling),Example:,Breakable join that fails after 1.e6 is reached.,All nodes within a tolerance of 1e-4 are connected.,BJOIN, 1, 333, 1.E-4, FOMO, 1.E6,SET1, 333, 31, THRU, 2000,
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